Texas secession movements
Texas secession movements, also known as the Texas independence movement or Texit, refers to both the secession of the U.S. state of Texas during the American Civil War as well as activities of modern organizations supporting such efforts to secede from the United States and become an independent sovereign state. The U.S. Constitution does not specifically address the secession of states, and the issue was a topic of debate after the American Revolutionary War until the American Civil War, when the U.S. Supreme Court ruled in Texas v.
Source: Wikipedia — Texas secession movements (CC BY-SA 4.0)